To increase accuracy, add the storage volume from your pipe based on the values listed in the graph.
Now that you know the volume of air consumed by leaks, a simple assumption is one leak for every 1 to 2 scfm of leak load.
Start by checking for audible leaks. Turn off everything that is making noise and slowly walk along the air piping. If there is a large leak present, you should be able to hear it.
An air leak can create a static charge, acting like a magnet for dust and other contaminants floating around your shop. Watch for visible signs of leaks, e.g., black grimy film or fuzziness around the leak area.
Another simple way to locate leaks is to apply soapy water around common leak locations - threaded pipe fittings, quick disconnects, filter/regulator gaskets and drains - and look for expanding bubbles.
ULTRASONIC LEAK DETECTION
The most comprehensive method of finding leaks uses an ultrasonic leak detector to filter out background noises and focus on the frequency of an air leak to identify small - yet significant - leaks which would otherwise go undetected.
It will cost a few thousand dollars to purchase an ultrasonic leak detector yourself. Consider hiring a service provider who has experience using the ultrasonic technology to find the leaks for you. Depending on the size of the area, they may be able to find and tag all of your leaks for only a few hundred dollars.
Check with your local utility company to see if they offer energy incentives to help cover the cost.
THE COST OF AIR LEAKS
Detecting air leaks can cost you time and money, so it makes sense to convert your leak volume into a dollar amount to justify the audit and repairs. Assuming electrical power costs $0.10/kWh, use the following formula to determine the cost of your system’s leaks:
Cost = 0.027 x (scfm from graph) x (hours per year compressor power is on)
For example, if your 60-gallon compressor has power on and is available to run six hours per day, five days a week and takes 30 seconds to drop 10 psi, you could be losing $631.80 on an annual basis.
0.027 x 15 scfm x (6 hours/day x 5 days/week x 52 weeks/year) = $631.80
This is based on a compressor operating stop/start. Depending on compressor design, control method and running hours, this could increase to more than $9,000 if you have a modulating-type rotary screw compressor running around the clock.
It is always important to be proactive to keep air leaks under control. If you hear or feel a leak, take action to repair it. It is a simple fix that will help to preserve your system and improve your overall efficiency.
If you’re upgrading your system, invest a little more money up front for quality components and engineered piping systems that use connection methods other than threaded fittings to minimize the potential for leaks and save money over the life of the system.
Being cognizant of wasted compressed air is paramount to achieving a best-in-class air system.
Elisabeth Kjellberg and Carlos Estrella are air system audit engineers with Ingersoll Rand Industrial Technologies. Ingersoll Rand is a world leader in creating and sustaining safe, comfortable and efficient environments in commercial, residential and industrial markets. www.ingersollrand.com. Its Industrial Technologies sector provides products, services and solutions that enhance our customers’ energy efficiency, productivity and operations.